Continuation of a Cooperative Group of Radiation Therapy Research and Clinical Centers for the purpose of conducting joint clinical investigations. This group has undertaken clinical trials and other cooperative studies in an endeavor to advance knowledge in the curative and palliative management of cancer. It will be possible, through the collaboration of the radiotherapy centers joined in the Radiation Therapy Oncology Group, to provide an adequate number of patients to answer significant questions in the treatment of cancer not possible on the basis of the number of patients seen in any one institution. The Group is committed to multi-disciplinary studies, both by the development of groups protocols involving the collaboration of Medical Oncologists and Surgeons, as well as establishing close liaison with other cooperative groups and the development of inter-group protocols. Such multi-disciplinary protocols exist or are about to be undertaken with ECOG, COG, CCSG, and GOG. A sophisticated biostatistical center, as an integral part of the Radiation Therapy Oncology Group, is ensuring satisfactory methodology of the studies and aids in establishing an order or priorities for studies which are of the greatest importance and can yield answers in a reasonable period of time.